Modelling - A smooth, gradual descent/rise?
Yes, actually! What you want for this task is proportional editing! If you'll look in the image below, you can access it via that icon, or by pressing 'O'. You have several falloffs to choose from, and you can choose if it should be affected by connected vertices, or anything under the circle (it makes a wide circle like when you use the brush select, and scrolling with the mousewheel adjusts the area of influence).